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lazy.tramp@gmail.com
science forum beginner
Joined: 12 Apr 2006
Posts: 1
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 Posted: Wed Apr 12, 2006 8:08 pm Post subject:
Simple question about magnet and metal
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Hi,
I know that the magnetic field doesn't do any work to particles. I
wonder why the magnet can make metal move. Base of Lorenz Force, if the
object does not move, therefore, there shouldn't be any force apply on
the object. Then, how can those stationary object moves without initial
velocity.
Thank you |
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Don Kelly
science forum Guru Wannabe
Joined: 30 Apr 2005
Posts: 166
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| Posted: Thu Apr 13, 2006 2:09 am Post subject:
Re: Simple question about magnet and metal
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<lazy.tramp@gmail.com> wrote in message
news:1144872519.582327.158010@i39g2000cwa.googlegroups.com...
| Quote: | Hi,
I know that the magnetic field doesn't do any work to particles. I
wonder why the magnet can make metal move. Base of Lorenz Force, if the
object does not move, therefore, there shouldn't be any force apply on
the object. Then, how can those stationary object moves without initial
velocity.
Thank you
------------ |
There are physical theories about the effect of a magnet on the metal -
skipping these, the magnetic field is roughly analogous to a gravitational
field which tries to pull an object down to a minimum energy position.
Potential energy of a mass at the bottom of a hill is lower than at the top
of the hill. However the mass cannot fall further but there is still a force
acting on it. {force =-d(mgh)/dh =- mg (h measured upward so force is
down)}
Putting a ferromagnetic material into a magnetic field changes the field
distribution and the stored energy in the field. There is a force acting to
minimise the field stored energy and this in many cases means a force trying
to minimise the distance between the magnet and the object. The force can be
found from the rate of change of stored energy with position (as is true of
a gravitational field){force in x direction =-d(stored magnetic field
energy)/dx ---similar for y and z directions}.
Note that putting aluminum into the field results in no noticeable effect. A
ferromagnetic material has a high permeability which modifies the field and
a force exists. There is another way to look at this- Maxwell shear forces -
same results.
On a gross basis, Lorentz forces are not involved.
--
Don Kelly @shawcross.ca
remove the X to answer
----------------------------
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Pieter
science forum beginner
Joined: 26 Jun 2005
Posts: 7
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| Posted: Thu Apr 13, 2006 9:40 pm Post subject:
Re: Simple question about magnet and metal
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On 12 Apr 2006 13:08:39 -0700, lazy.tramp@gmail.com wrote:
| Quote: | Hi,
I know that the magnetic field doesn't do any work to particles. I
wonder why the magnet can make metal move. Base of Lorenz Force, if the
object does not move, therefore, there shouldn't be any force apply on
the object. Then, how can those stationary object moves without initial
velocity.
Thank you
|
Hi, a magnetic field does influence particles. It influences the spin
(google on it for more info, try MRI, magentic resonance etc). In a
metal like iron, atoms orient their spin in the direction of the
field, and form a magnet themselves this way. The created fields give
the force (feel the..).
This is very, very simplified but a general idea. Google on things
like barkhausen effect etc. for more info.
Regards,
Pieter |
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RP
science forum Guru
Joined: 07 May 2005
Posts: 348
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| Posted: Mon Apr 17, 2006 5:30 am Post subject:
Re: Simple question about magnet and metal
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lazy.tramp@gmail.com wrote:
| Quote: | Hi,
I know that the magnetic field doesn't do any work to particles. I
wonder why the magnet can make metal move. Base of Lorenz Force, if the
object does not move, therefore, there shouldn't be any force apply on
the object. Then, how can those stationary object moves without initial
velocity.
Thank you
|
The object is composed of charged particles that are all in motion wrt
the magnet.
Richard Perry |
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<miltonpugh@sbcglobal.
science forum beginner
Joined: 18 Sep 2005
Posts: 21
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| Posted: Mon May 01, 2006 4:26 am Post subject:
Re: Simple question about magnet and metal
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The conventional magnetic field is a wysiwyg physical illusion. A non
entitie. A conceptual idea only.
A magnet does produce a dynamic electrical field tangential (in electrical
field topology) to a typical bar magnet with a clockwise or counterclockwise
field pattern (as viewed by the target) and the circular direction
determines the type of magnetic pole will be demonstrated, N or S.
Any charged partical in motion which is within the dynamic electrical field
having that curved clockwise or counterclockwise pattern, will experience a
(re-direction of its inertia). we percieve this re-direction of inertia as a
displacement which appears to have been acted upon by an invisible force,
but the force has actually been demonstrated by the function of a cause and
effect relationship where the dynamic electrical field is part of the cause
of a redirection of inertia type effect causing the grand illusion of action
at a distance caused by a magnetic force being a contiguous force requiring
a medium, when in fact only the dynamic electrical field is propagated
without a medium as an avalanch propagation. A charged partical in motion
will respond to a single
dynamic electrical field from a single frame or it can respond to multiple
fields from multiple frames as the multiple frames with multiple fields
present an aggregate field with additive and cancelling field attributes in
a single instant of time with the overall response by the charged partical
in motion appearing to have adapted the transformations. Kind regards, Lee
Pugh
<lazy.tramp@gmail.com> wrote in message
news:1144872519.582327.158010@i39g2000cwa.googlegroups.com...
| Quote: | Hi,
I know that the magnetic field doesn't do any work to particles. I
wonder why the magnet can make metal move. Base of Lorenz Force, if the
object does not move, therefore, there shouldn't be any force apply on
the object. Then, how can those stationary object moves without initial
velocity.
Thank you
|
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